1. Field of The Invention
The present invention relates to a zero insertion force (ZIF) socket, and especially to a ZIF socket having locking means for retaining the socket in either a closed status or an open status.
2. The Prior Art
Conventional zero insertion force (ZIF) sockets normally comprise a cover defining a plurality of upper passageways therein and slidably engaging with a base having a corresponding number of lower passageways retaining contacts therein. The upper passageways and the lower passageways are in constant communication with each other when the cover is moved with respect to the base. A cam is received in a space defined between the cover and the base and operative to move the cover with respect to the base thereby positioning the socket at either an open status ready for insertion of pins of a CPU package or a closed status forcing the pins of the CPU package to abut against the corresponding contacts. When the socket is in the open status, the pins of the CPU package are inserted into the upper passageways and the lower passageways with a substantially zero insertion force, but are not in electrical contact with the contacts retained in the lower passageways. The cam is then operated to drive the cover to move laterally relating to the base thereby urging the pins of the CPU package to electrically connect with the contacts of the base. U.S. Pat. No. 5,730,615 which belongs to the same assignee of this application has disclosed a socket having a cover movably engaged with a base and positioning means including a vertical protrusion on the side face of the base to cooperate with a pair of spaced shallow regions, named front shallow region and rear shallow region, formed in the interior portion of the cover. Therefore, the protrusion of the base may be received within the front shallow region in the cover when the socket is in an open status, and within the rear shallow region when the socket is in a closed status. However, the positioning of the vertical protrusion in either the front shallow region or the rear shallow region is not strong enough to guarantee unwanted movement of the vertical protrusion. It is requisite to provide locking means to fix the cover to the base in either a closed status or an open status.